1. Field of the Invention
The present invention relates to an organic semiconductor element having an organic semiconductor film and a method for manufacturing thereof. Moreover, the present invention relates to a semiconductor device provided with an organic semiconductor element and a method for manufacturing thereof.
2. Description of the Related Art
In recent years, a display device provided with a thin film transistor (hereinafter, a TFT) having a thin film semiconductor has been studied and put into practical use. A high-resolution display device can be achieved since a large number of pixels can be constituted in the display device provided with a TFT. Moreover, it is known that the display device provided with a TFT can be operated in low power consumption, since it can be operated in low voltage compared with a CRT. Furthermore, the display device provided with a TFT occupies small space, since a display can be constituted without using a large scale of a display tube like a CRT. Thus, such a display device provided with a TFT is widely used for a display portion of a personal computer, a PDA, a TV, or the like. The display device which is made to be thinner, lighter, and more flexible is required in future, and it is more expected to use a resin substrate such as a plastic. However, most of conventional TFTs have been manufactured by using an inorganic semiconductor material such as amorphous silicon or crystalline silicon as a semiconductor film. Therefore, use of a resin substrate and the like such as a plastic is limited since processing temperature of 350° C. or more is needed for forming the semiconductor film in the case where a TFT is manufactured by using an inorganic semiconductor material.
On the other hand, an organic TFT in which an organic semiconductor is used as a semiconductor film has been studied. An organic TFT has high flexibility since an organic material is used. Moreover, as a material for a substrate of an organic TFT, a resin material such as a plastic can be used since an organic TFT can be formed at lower temperature than a device using an inorganic semiconductor. Therefore, a device which is light and flexible can be obtained. Moreover, as for an organic TFT, it is expected that not only process such as a printing method, an ink-jetting method, and a vapor deposition method can be simplified, but the manufacturing cost of a device can be also suppressed since an inexpensive material for a substrate can be used, and thus it is advantageous in view of the cost.
However, an organic semiconductor is oxidized or decomposed due to exposure to water, light, or oxygen. Therefore, an organic semiconductor has a disadvantage that electric properties are deteriorated by being laid in atmospheric air.